This invention relates to direct current power supply circuits for photomultiplier tubes.
The power supply source of the present invention makes use of an inverter energised from a d.c. source and rectifier means for providing a high voltage supply for a photomultiplier tube. For some purposes, for example cathode ray tubes and electron microscopes, a power supply circuit is required to maintain a substantially stable high voltage. For photomultiplier tubes, however, it is often required that the voltage should be controlled in a manner dependent on the current drawn from the power supply circuit. Because of the wide range of magnitudes of the anode current and because of the voltage current characteristics required, the appropriate regulation of the voltage presents problems. In particular, the range of light intensity over which the tube will operate between the minimum at which a usable signal is obtained and the maximum when the tube saturates is restricted unless the supply voltage and particularly the dynode supply voltage is varied in accordance with the current. U.S. Pat. Nos. 2,971,433, 3,476,940 and 3,653,763 illustrate prior arrangements for providing a high voltage supply with suitable voltage/current characteristics.